Dark mode blog post

[kh-ub-ayb]

Added a new blog post detailing the process of implementing dark mode for the Sugar Labs website.
The post covers the motivation, challenges faced during development, debugging steps, and the final solution providing valuable insights for contributors who want to work on theming and accessibility features.
#440

[github-actions]

🎉 All Checks Passed!

Status: ✅ Ready to merge

✅ Completed Workflows

Workflow	Status	Details
🔨 Continuous Integration	✅ Passed	Build completed successfully
📝 Code Linting	✅ Passed	All formatting and style checks passed

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🚀 This PR is ready for review and can be safely merged to main branch!

Great work! Your code meets all quality standards. 👏

[kh-ub-ayb]

@pikurasa @sa-fw-an plz review

[github-actions]

🎉 All Checks Passed!

Status: ✅ Ready to merge

✅ Completed Workflows

Workflow	Status	Details
🔨 Continuous Integration	✅ Passed	Build completed successfully
📝 Code Linting	✅ Passed	All formatting and style checks passed

---

🚀 This PR is ready for review and can be safely merged to main branch!

Great work! Your code meets all quality standards. 👏

[kh-ub-ayb]

@pikurasa plz review

[pikurasa]

The post itself is almost ready for publication. However, there are a few things:

• Please limit this PR to only changes related to the blog post. I see some changes to the contact page and assets. Those should be in a different PR.
• You need to make descriptive commit messages that tell us what you changed. Right now, you have messages that say "update blog post" and one that is very long, without file names. Please tell us what is being changed in a short message. You can read an article like https://www.baeldung.com/ops/git-commit-messages for ideas on best practices.
• I think that a reader, after reading your article, may want to try dark mode. It may be obvious to you, but I think you should add a screenshot that shows where the toggle button us to direct them to "try it out".